AquaCare/AquaCare.Persistence/Datenbank.cs

using Microsoft.Data.Sqlite;
using System;
using System.Collections.Generic;

namespace AquaCare.Persistence
{
    public class Datenbank
    {
        private const string ConnectionString = "Data Source=AquaCare.db";

        // Initialisiert die Datenbank und erstellt die Tabelle, falls sie nicht existiert
        public void InitializeDatabase()
        {
            using (var connection = new SqliteConnection(ConnectionString))
            {
                connection.Open();

                string tableCommand = @"
                    CREATE TABLE IF NOT EXISTS Werte (
                        ID INTEGER PRIMARY KEY AUTOINCREMENT,
                        Datum TEXT NOT NULL,
                        Temperatur REAL NOT NULL,
                        PHWert REAL NOT NULL,
                        Nitrat REAL NOT NULL,
                        Ammoniak REAL NOT NULL
                    );";

                using (var command = new SqliteCommand(tableCommand, connection))
                {
                    command.ExecuteNonQuery();
                }
            }
        }

        // Fügt einen neuen Wert in die Datenbank ein
        public void AddValue(DateTime datum, double temperatur, double phWert, double nitrat, double ammoniak)
        {
            using (var connection = new SqliteConnection(ConnectionString))
            {
                connection.Open();

                string insertCommand = @"
                    INSERT INTO Werte (Datum, Temperatur, PHWert, Nitrat, Ammoniak)
                    VALUES (@Datum, @Temperatur, @PHWert, @Nitrat, @Ammoniak);";

                using (var command = new SqliteCommand(insertCommand, connection))
                {
                    command.Parameters.AddWithValue("@Datum", datum.ToString("yyyy-MM-dd"));
                    command.Parameters.AddWithValue("@Temperatur", temperatur);
                    command.Parameters.AddWithValue("@PHWert", phWert);
                    command.Parameters.AddWithValue("@Nitrat", nitrat);
                    command.Parameters.AddWithValue("@Ammoniak", ammoniak);

                    command.ExecuteNonQuery();
                }
            }
        }

        // Ruft alle gespeicherten Werte aus der Datenbank ab und gibt sie als Strings zurück
        public List<string> GetValues()
        {
            var values = new List<string>();

            using (var connection = new SqliteConnection(ConnectionString))
            {
                connection.Open();

                string selectCommand = "SELECT Datum, Temperatur, PHWert, Nitrat, Ammoniak FROM Werte;";

                using (var command = new SqliteCommand(selectCommand, connection))
                using (var reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        string value = $"Datum: {reader.GetString(0)}, Temperatur: {reader.GetDouble(1)}°C, " +
                                       $"pH-Wert: {reader.GetDouble(2)}, Nitrat: {reader.GetDouble(3)} mg/L, " +
                                       $"Ammoniak: {reader.GetDouble(4)} mg/L";
                        values.Add(value);
                    }
                }
            }

            return values;
        }

        // Ruft alle gespeicherten Werte aus der Datenbank ab und gibt sie als Objekte zurück
        public List<Wert> GetValuesAsObjects()
        {
            var werte = new List<Wert>();

            using (var connection = new SqliteConnection(ConnectionString))
            {
                connection.Open();

                string selectCommand = "SELECT Datum, Temperatur, PHWert, Nitrat, Ammoniak FROM Werte ORDER BY Datum ASC;";

                using (var command = new SqliteCommand(selectCommand, connection))
                using (var reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        werte.Add(new Wert
                        {
                            Datum = reader.GetString(0),
                            Temperatur = reader.GetDouble(1),
                            PHWert = reader.GetDouble(2),
                            Nitrat = reader.GetDouble(3),
                            Ammoniak = reader.GetDouble(4)
                        });
                    }
                }
            }

            return werte;
        }
    }

    // Klasse zur Darstellung eines Wertes
    public class Wert
    {
        public string Datum { get; set; }
        public double Temperatur { get; set; }
        public double PHWert { get; set; }
        public double Nitrat { get; set; }
        public double Ammoniak { get; set; }
    }
}